Storage devices, like fixed disks or removable drives, are usually divided into partitions. A Master Boot Record (MBR) is a special type of boot sector at the very beginning of the partitioned storage device intended for use with IBM PC-compatible systems. The MBR can include a partition table describing how the logical partitions, containing file systems, are organized on that medium. The MBR itself is not located in a partition; it is located at a first sector of the device (physical offset 0), preceding the first partition. The MBR functions as an operating system independent chain boot loader in conjunction with each partition's Volume Boot Record (VBR).
The partition table generally includes two types of addressing schemes. A first type is a Cylinder-Head-Sector (CHS) addressing scheme, which is becoming antiquated and no longer has a direct physical relationship with data stored on the latest-developed disks. The second type of addressing is Logical Block Addressing (LBA), which is a simple linear addressing scheme in which blocks are located by an integer index, with the first block being LBA 0, the second LBA 1, and so on.
Virtual environments have virtualized storage devices that mimic physical storage devices. The virtualized storage devices are partitioned and include an MBR. However, importation of storage devices into a virtual environment can be difficult, especially if the disk geometries are dissimilar.